The present invention relates to the collection of material samples, as for forensic, scientific, or diagnostic purposes, and more particularly, to devices for collecting such samples and preserving them from contamination prior to laboratory analysis.
Crime scene evidence is collected to establish facts related to a crime or a suspected crime and for identification and/or elimination of suspects and may be presented at a trial for the determination of guilt or innocence of accused individuals. Often, the evidence includes objects, documents, fingerprints, photographs of the scene, and the like. Additionally, the evidence may include unknown substances or substances with a suspected identity, where the identity needs to be determined or confirmed. Such substances may be very small in quantity, may be dispersed over a comparatively large area, and may include materials such as: body fluids, hairs, flakes of skin, fibers, drugs, various chemicals, gunpowder residue, flammable materials, tobacco ashes, cosmetics, and the like. Such materials may be collected at a scene and subjected to chemical and/or DNA analysis for identification or for association with a particular individual.
For collecting substance samples, investigators typically use fibrous swabs, such as swabs made of fibers of cotton, cellulose, rayon, polyester, and other types of fibers. Such swabs not only absorb liquids and solids entrained in liquids but also trap dry substances such as particulate materials. The swabs are kept in closed bags or containers prior to use to maintain sterility and are replaced in such containers after use to avoid contamination of the sample gathered. After replacement of a swab in a container, the container is usually marked with a time and date and identity of the investigator and other information to establish a chain of custody of the sample.
Conventional swabs are formed of a “stick” such as a shaft of wood, tubular plastic, or tubular or rolled paper with a pad of cotton or other fiber, sponge material, or other absorbent material attached to the end of the shaft, either mechanically or by an inert adhesive. A problem with conventional swabs is that there is a danger of contamination of the sample if it is necessary to put the swab down, for example, to open a bag or container in which the swab will be placed. Also, if it is necessary to set the swab down to dry, in a propped up condition or extending over the edge of a table, there is a risk of contamination of the sample.